The present invention relates to determination of a vehicle crash condition for protection of an occupant, and is particularly directed to use of sensed crash-induced influence on the occupant to determine the occurrence of the vehicle crash condition.
Occupant protection systems for use in vehicles are known in the art. One example type of protection system includes an actuatable inflatable restraint module, which has an inflatable restraint that is commonly referred to as an air bag. A controller determines whether the restraint module is to be actuated to inflate the air bag within a vehicle passenger compartment. The restraint module is actuated by the controller upon the occurrence of a predetermined condition for which a vehicle occupant is to be restrained. For example, when a crash sensor that is operatively connected to the controller senses a vehicle condition indicative of a vehicle crash condition, the restraint module is actuated.
In one example type of such an occupant protection system, the crash sensor is an accelerometer. The accelerometer is typically sensitive along a single axis (e.g., a fore-to-aft vehicle axis). Typically, such an accelerometer can have a full-scale sensitivity of 50 G, but may not be sensitive enough to detect pre-crash braking. Often it may be desirable to detect pre-crash braking (i.e., as a pre-cursor to a potential vehicle crash condition). Also, rough roads may affect the accelerometer. The effect imposed upon the accelerometer by rough roads is inversely related to the sensitivity of the accelerometer.
In view of the characteristics of the accelerometer, there is often a need for a redundant xe2x80x9csafingxe2x80x9d crash sensor in some occupant protection systems. The accelerometer is a primary sensor in such a system, and both the primary and the safing sensor must respond to a condition (e.g., vehicle acceleration) that is indicative of a vehicle crash condition in order for the protection module to be actuated.
One type of known safing sensor is an acceleration-activated mechanical switch. However, rough roads can adversely affect such a safing sensor in a manner similar to the adverse affect imposed upon the primary sensor. Thus, there are significant challenges to protection system designers to develop actuation algorithms that avoid the adverse influence of rough roads and the like within a system that utilizes conventional sensors. One way to avoid such challenges is to sense or determine a vehicle crash condition without the use of such conventional sensors.
In accordance with one aspect, the present invention provides a vehicle crash determination arrangement. The arrangement includes means for sensing a weight value associated with an occupant located on a seat. Means determines a weight-based center characteristic associated with the occupant using the sensed weight value. Means determines occurrence of a vehicle crash using change in the determined weight-based center characteristic associated with the occupant and outputs a signal indicative of the determination of crash occurrence.
In accordance with another aspect, the present invention provides an occupant protection system for an occupant located on a vehicle seat. The system includes an actuatable occupant protection device. Control means controls actuation of the device. A vehicle crash determination arrangement of the system includes means for sensing a weight value associated with an occupant located on a seat. The arrangement includes means for determining a weight-based center characteristic associated with the occupant using the sensed weight value. The arrangement includes means for determining occurrence of a vehicle crash using change in the determined weight-based center characteristic associated with the occupant and for outputting a signal indicative of the determination of crash occurrence to the control means.
In accordance with another aspect, the present invention provides a method of determining the occurrence of a vehicle crash. A weight value associated with an occupant located on a seat is sensed. A weight-based center characteristic associated with the occupant is determined using the sensed weight value. Occurrence of a vehicle crash is determined using change in the determined weight-based center characteristic associated with the occupant. A signal indicative of the determination of crash occurrence is output.